Corrected QT Interval (QTc) Calculator
The QT interval represents the duration of ventricular electrical systole, it is measured from the beginning of the QRS complex to the end of the T wave.
The QT interval varies depending on hearr rate, it decreases at faster HR and it lengthens at slower HR, so it should undergo adequate rate correction (corrected QT or QTc).
To calculate the corrected QT interval (QTc) you need the QT interval duration and heart rate.
Corrected QT Interval (QTc)
QT interval duration
QT interval duration in ms:
Click if you prefer to enter the number of small squares.
Number of small squares:
Click if you prefer to enter the QT interval duration in ms.
Click if you prefer to enter the R-R interval.
Click if you prefer to enter the heart rate.
- Long QTc: greater than 460 ms in children under the age of 15, 450 ms in men, and 470 ms in women 1.
- Short QTc interval: less than 340 ms is accepted as pathological.
We use Framingham corrections 2 in this calculator because it has more uniform correction over a wide range of heart rate 3.
Remember, this calculator is not 100% reliable, and it is not a substitute for traditional methods of corrected QT interval calculation, nor electrocardiogram evaluation made by a doctor or competent professional.
How to use the corrected QT Calculator
Example: calculate QT interval, from the beginning of the QRS to the end of the T wave